Add basic sink #dipping effects

This is largely taken from xNetHack with a few minor changes.  Dipping a
potion into a sink can help with item identification by producing the
potionbreathe effect (or a sink-specific effect, for a couple potions).
Dipping other items will just run water over them.  I also added the
capability to wash your hands at a sink.

include/extern.h

@@ -472,6 +472,7 @@ extern int dodrop(void);
 extern boolean boulder_hits_pool(struct obj *, coordxy, coordxy, boolean);
 extern boolean flooreffects(struct obj *, coordxy, coordxy, const char *);
 extern void doaltarobj(struct obj *);
+extern void polymorph_sink(void);
 extern void trycall(struct obj *);
 extern boolean canletgo(struct obj *, const char *);
 extern void dropx(struct obj *);
@@ -975,6 +976,7 @@ extern void dipfountain(struct obj *);
 extern int wash_hands(void);
 extern void breaksink(coordxy, coordxy);
 extern void drinksink(void);
+extern void dipsink(struct obj *);
 
 /* ### hack.c ### */
 

src/do.c

@@ -7,7 +7,6 @@
 
 #include "hack.h"
 
-static void polymorph_sink(void);
 static boolean teleport_sink(void);
 static void dosinkring(struct obj *);
 static int drop(struct obj *);
@@ -352,7 +351,7 @@ trycall(struct obj *obj)
 
 /* Transforms the sink at the player's position into
    a fountain, throne, altar or grave. */
-static void
+void
 polymorph_sink(void)
 {
     uchar sym = S_sink;

src/fountain.c

@@ -694,4 +694,47 @@ drinksink(void)
     }
 }
 
+void
+dipsink(struct obj *obj)
+{
+    boolean try_call = FALSE;
+
+    if (obj == &cg.zeroobj || obj == uarmg) {
+        (void) wash_hands();
+        return;
+    } else if (obj->oclass != POTION_CLASS) {
+        You("hold %s under the tap.", the(xname(obj)));
+        if (water_damage(obj, (const char *) 0, TRUE) == ER_NOTHING)
+            pline("Nothing seems to happen.");
+        return;
+    }
+
+    /* at this point the object must be a potion */
+    You("pour %s%s down the drain.", (obj->quan > 1L ? "one of " : ""),
+        the(xname(obj)));
+    switch (obj->otyp) {
+    case POT_POLYMORPH:
+        polymorph_sink();
+        try_call = TRUE;
+        break;
+    case POT_OIL:
+        if (!Blind) {
+            pline("It leaves an oily film on the basin.");
+            try_call = TRUE;
+        }
+        break;
+    default:
+        /* hero can feel the vapor on her skin, so no need to check Blind or
+           breathless for this message */
+        pline("A wisp of vapor rises up...");
+        /* NB: potionbreathe calls trycall or makeknown as appropriate */
+        if (!breathless(gy.youmonst.data) || haseyes(gy.youmonst.data))
+            potionbreathe(obj);
+        break;
+    }
+    if (try_call && obj->dknown)
+        trycall(obj);
+    useup(obj);
+}
+
 /*fountain.c*/

src/potion.c

@@ -2269,6 +2269,16 @@ dodip(void)
                 return ECMD_TIME;
             }
             ++drink_ok_extra;
+        } else if (IS_SINK(here)) {
+            Snprintf(qbuf, sizeof(qbuf), "%s%s into the sink?", Dip_,
+                     flags.verbose ? obuf : shortestname);
+            if (y_n(qbuf) == 'y') {
+                if (!is_hands)
+                    obj->pickup_prev = 0;
+                dipsink(obj);
+                return ECMD_TIME;
+            }
+            ++drink_ok_extra;
         } else if (is_pool(u.ux, u.uy)) {
             const char *pooltype = waterbody_name(u.ux, u.uy);